Figure 5. Human DMPK A expression affects mitochondrial function and cell viability.

(A) C₂C₁₂ myoblasts were grown under different culture conditions and transfected with YFP-hDMPK A or C. The fraction of viable YFP positive cells was determined after 20 hours. When supplied with galactose and pyruvate, YFP-hDMPK A-expressing cells showed a significantly lower viability than YFP-hDMPK C-expressing cells (P<0.01, n = 3, >100 cells analyzed per experiment). (B) The MMP was determined in HeLa cells expressing YFP-hDMPK A or C. YFP-hDMPK A–expressing cells without clustered mitochondria showed a clear MMP signal (upper panels). No TMRM signal was found in YFP-hDMPK A–expressing cells with clustered mitochondria (middle panels, asterisks). YFP-hDMPK C–expressing cells demonstrated a clear mitochondrial signal (lower panels). Bars, 10 µm. (C) The MMP in YFP-hDMPK A–expressing cells was almost completely abolished and significantly lower than in YFP-hDMPK C and non-transfected (NT) cells (P<0.001, n = 3, >35 cells per experiment).